While it has been recognized for many years that the anterior pituitary gland secretes two hormones which control the gonads-- follicle stimulating hormone and luteinizing hormone--we know far less about the control of secretion rate and mechanism of action for FSH than for LH. This application for a Program Project Grant outlines a multidisciplinary research effort aimed toward advancing our understanding of the control of the secretion rate of FSH by the anterior pituitary gland and of the mechanisms of action of the hormone on the ovary and testis. The application consists of the following projects and cores: Project I. Early Events in the Stimulation of Immature Porcine Granulosa Cells by FSH Project II. Regulation of FSH Secretion by the Perifused Pituitary Gland. Project III. Photoperiodic Control of FSH Secretion. Project IV. Neural Regulation of FSH Release: GnRH Release and Feedback Mechanisms Project V. Stress & Reproductive Function Project VI. Genes Encoding Gonadal FSH-Regulatory Hormones Core A. Radioimmunoassay Core B. Administration The present proposal represents the collaborative venture of 11 faculty members interested in reproductive endocrinology and representing 5 University departments to develop a unified program to improve our understanding of FSH. We expect that this combined thrust of in vivo and in vitro methodology, encompassing every level of the hypothalamic-pituitary-gonadal axis in experimental models and in humans, will add considerably to our basic knowledge about FSH and make it more feasible to consider FSH as a target in fertility and contraceptive research.